User registration and location management for mobile telecommunications systems

ABSTRACT

A method of use of a UMTS telecommunications network, comprising utilizing UMTS signalling to indicate changes in an IP sub-network. To register a Mobile Terminal (MT) or to update its location within the network, signalling relevant to the IP domain is transmitted with UMTS signalling in an integrated approach. This reduces the number of signalling messages that are required and minimizes delays.

BACKGROUND OF THE INVENTION

This invention relates to user registration and location management formobile telecommunications systems. In particular, it relates toUniversal Mobile Telecommunications Service (UMTS) systems, when used toprovide connectivity between an IP (Internet Protocol) capableend-device and an IP-based network.

When a UMTS user switches on his mobile terminal (I), the user needs tobe registered with the UMTS network. Similarly, when the user movesaround the area covered by the network, location management proceduresneed to take place in order to allow the user to be provided withservices.

The initial registration process normally involves requesting forregistration on the network, authentication of the user by the network,registration of the user and informing the home location register (HLR)of the users current whereabouts. This takes place at the UMTS level.

At the IP (Internet Protocol) level, there are three scenarios toconsider when the user switches on an IP capable terminal. These are:

(1) the user has a static home IP address, (2) the user requires adynamic home IP address from the UMTS operator, and (3) the userrequires a dynamic home IP address from a body outside the UMTS domain.

In any case, a mobile IP registration with the home agent (HA) andperhaps the foreign agent (FA) needs to take place before the user cansuccessfully engage in a data transaction using the Internet Protocol.

The current solution for the registration of data (IP) users in UMTSwith mobile IP relies on the use of two, subsequent, registrations, thefirst at the UMTS level and the second at the IP level. This is shown inFIG. 1.

The user of a mobile terminal switches on his mobile terminal MT1 andrequires registration with the UMTS network. He sends a message 2requesting registration which passes through a radio network controller(RNC) 3 (which may also be the foreign agent (FA) for the IP protocol)to a switching centre with a visiting location register (VLR) 4. This inturn requests user information from any previous visiting locationregister 5 which the user may have last received service from, or fromthe user's home location register (HLR) 6. This sends back informationconcerning the user to the new VLR 4 and then an authentication request7 and reply 8 are sent to and received from the mobile terminal 1. Afterthis authentication, registration of the mobile terminal is complete anda register complete message 9 is sent to the terminal. Also, a message10 is sent to the HLR informing the HLR of the new location of theterminal.

If IP registration is also required, then a further IP registration stepalso has to take place with conventional systems.

Once UMTS registration is complete, the mobile terminal 1 sets up a UMTSdata channel 11. The mobile terminal 1 sends an FA router solicitationmessage 12 to the new RNC/FA 3 and this in turn sends an FAadvertisement 13 back to the mobile terminal over the data channel. Themobile terminal then sends a registration request which passes throughthe RNC/FA 3 and onwards to the home agent 14. This then sends back aregistration reply 15 to the mobile terminal and IP registration iscomplete. The foreign agent FA in IP is analogous to the VLR (visitinglocation register) in the UMTS domain.

Accordingly, two independent registration processes are necessary, firstthe UMTS registration and then the IP registration.

When a UMTS user moves around the area covered by the network, locationmanagement procedures need to take place in order to allow the user tobe provided with services. Location management under a single radionetwork controller (RNC) does not affect the IP level. However,inter-RNC location updates have to involve IP level mobility as well asUMTS mobility. This is because it is assumed that mobile IP foreignagents (FA's) and RNC's are co-located.

Conventionally, an analogous process to the conventional method ofregistration has been done. Firstly UMTS location update is done andthen, independently, a subsequent IP location update is done. This isshown in FIG. 2.

The location update procedures are similar in principle to theregistration updates of FIG. 1, except that the location update 16 isrequired for both IP and UMTS, rather than register updates. Apart fromthis, the procedures involve similar steps, mutatis mutandis.

In both the user registration and location management scenarios, thecomplete separation of the two procedures for UMTS and IP bringinefficiencies in the usage of the air-interface, and delays to theoverall registration or location update procedure.

The present invention arose in an attempt to reduce these inefficienciesand to reduce the time taken for the overall registration procedure orfor the overall location update procedure.

It is known from the paper by Clapton A J et al entitled “UMTS—themobile part of broadband communications for the next century”, BTTechnical Journal, GB, BT Laboratories, vol. 16, no. 2, 1 Apr. 1998,pages 120–131, XP000750524 ISSN=1358−3948 to provide a method for amobile terminal in a UMTS and IP telecommunications network to registerand/or update its location.

BRIEF SUMMARY OF THE INVENTION

The present invention is characterised over the disclosure of theClapton paper by using UMTS messages to transmit IP information for IPregistration and/or IP location update.

Mobile-IP specifications allow for link-layer mechanisms to be used todiscover a foreign agent (FA) or to detect a change in the sub-network.In a preferred embodiment of the invention, accordingly, the UMTS levelmobility-management (link-layer) is used for FA discovery.

More specifically, the method may comprise using UMTS ‘register request’and ‘register complete’ messages for detecting FA information.

Preferably, additional fields of information are sent with the ‘registerrequest’ message and with the ‘register complete’ message.

The fields which may be sent with the ‘register request’ message are:(1) type of home address, (2) type of COA (care of address), (3) home IPaddress, (4) home agents address, and (5) last used COA.

The additional field for the ‘register complete’ messages may be (1)home address, (2) COA type and (3) COA.

In further embodiments relating to location management, the UMTS‘location update’ and ‘location update complete’ messages may be used.

Preferably, extra fields of information are provided in one or both ofthese messages. The fields which may be attached to the ‘locationupdate’ message are: (1) home address, (2) COA type and (3) COA.

The extra fields which may be attached to the ‘location update complete’message may comprise any of (1) type and (2) COA.

DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings in which:

FIG. 1 shows UMTS and IP registration procedures according to the priorart;

FIG. 2 shows UMTS and IP location update procedures according to theprior art;

FIG. 3 shows an integrated registration procedure according to thepresent invention; and

FIG. 4 shows an integrated location update procedure according to thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Referring to FIG. 3, in embodiments of the invention, the UMTS levelmobility-management (link-layer) may be used for FA discovery.Accordingly, the UMTS ‘register req’ and ‘register complete’ messagesare used for discovering the FA care-of-address (COA) or obtaining aco-located COA for a mobile terminal. Thus, in the Figure, when a mobileterminal 1 requires to register with a network, it sends out a modifiedregister request message 30 with the addition of various IP relatedfields.

These fields are:

(1) type of home address

(2) type of COA

(3) home IP address (optional)

(4) home agents address (optional)

(5) last used COA (optional)

Note that if the mobile terminal 1 is not IP capable, then theadditional fields are not used.

More particularly, the fields are the following:

(1) Type: this field identifies to the network if the mobile terminal 1has a static address or requires a dynamic address from the UMTSoperator, or requires a dynamic address from an entity outside the UMTSdomain. (2) Type of COA: this identifies if the mobile terminal is touse a co-located COA or a FA, the address in the COA field depends uponthis setting. (3) Home address: if the mobile is configured with astatic home address, this field identifies that address. If the mobiledoes not have a statically configured home address, this field isomitted. (4) Home agent: if the mobile has been configured staticallywith its home agent address, this field identifies it. Otherwise, thisfield is omitted. (5) Last used COA: this field contains the mobile'slast used COA, if any. Otherwise this field is omitted.

The ‘register req’, with attached IP fields is functionally similar tothe FA router solicitation 12 of FIG. 1.

The ‘register complete’ message is, from the IP perspective, the FAadvertisement. The additional IP fields in the ‘register complete’message are:

(1) home address: home address of the user (2) type: the type of COAused at present, co-located or foreign agent (FA) (3) COA: the COA.

If the user does not have a static address and the UMTS network couldnot obtain a home address for the user, then the user will be requiredto use IP level mechanisms to obtain one. The UMTS network will however,issue the user with the address of the FA or the co-located COA.

Subsequent to the register complete message 32, the mobile then uses aUMTS data channel to send a mobile-IP registration message 33 to the FA(or direct to the HA in case of a co-located COA). This procedure takesplace at the IP level, where a data channel 34 is set up over the UMTSradio interface for carrying IP control messages. The HA (or FA) thentransmits a registration reply message 35.

FIG. 4 shows an embodiment of the invention representing an integratedprocedure for location management with mobile IP and UMTS. The procedurediffers from that of the prior art in that the mobile terminal 40, inits ‘location update request’ transmission 41 also includes one or moreextra fields. The fields are:

(1) home address: home address of the user (2) type: the type of COAused at present, co-located or foreign agent (FA) (3) COA: the COA.

An authentication routine then follows and, once the UMTS level locationupdate is successfully completed, the RNC/FA checks whether a new COAneeds to be issued. They can do this because of the information that waspresented by the mobile terminal 40 in the ‘location update request’message 41. If a new COA needs to be issued, it is attached to a“location update complete” message 42. The extra fields of informationrequired within this message are (1) type and (2) COA. This message isused by the mobile terminal 40 at the IP level, as detection for mobileIP. A data channel is set up and the mobile terminal decides what itneeds and whether it needs to do anything in relation to registeringwith a new FA and HA and this takes place at a registration request step44. The mobile terminal registers either with a new RNC/FA 46 and withthe home agent (HA) 47. If route optimisation is enabled, then the newFA will re-register the user at the old FA.

Embodiments of the invention accordingly allow a reduction in signallingmessages that have to be transmitted across the air interface, duringregistration or during an inter-RNC location update, and minimise thedelay required to complete such location updates. In effect, therefore,valuable network resources are saved and overhead is reduced.

Embodiments of the invention in general utilise UMTS signalling fordetecting changes in the IP sub-network and integration of IP levelsignalling and UMTS level signalling. The invention may have wider usethan the two specific scenarios described (user registration andlocation management) and may be applied to other scenarios where IPsignalling is required.

Mobile IP information is sent during UMTS signalling for the reasonsdescribed above.

1. A method for a mobile terminal in a UMTS and IP mobiletelecommunications network to register its position by using UMTS‘register request’ messages, and/or UMTS ‘register complete’ messages,to transmit IP information for IP registration.
 2. A method as claimedin claim 1, wherein fields of information relevant to the IP domain aresent with the ‘register request’ message.
 3. A method as claimed inclaim 2, wherein the fields are: (1) type of home address, (2) type ofcare of address (COA), and, optionally, any of the following: (3) homeIP address, (4) home agents (HA) address and (5) last used COA.
 4. Amethod as claimed in claim 3, wherein additional fields of informationare sent with the ‘register complete’ message.
 5. A method as claimed inclaim 4, wherein the additional fields comprise (1) home address, (2)COA type and (3) COA.
 6. A method for a mobile terminal in a UMTS and IPmobile telecommunications network to update its location by using UMTS‘location update’ messages, and/or UMTS ‘location update complete’messages, to transmit IP information for IP location update.
 7. A methodas claimed in claim 6, wherein additional fields of information relevantto the IP domain are sent with the ‘location update’ message.
 8. Amethod as claimed in claim 7, wherein the additional fields comprise (1)home address, (2) COA type and (3) COA.
 9. A method as claimed in claim6, wherein additional fields are sent with the ‘location updatecomplete’ message.
 10. A method as claimed in claim 9, wherein theadditional fields comprise (1) type and (2) COA.